Wireless positioning systems generally refer to systems that track or locate a transmitter using wireless technologies, including the transmission and measurement of electromagnetic signals. Tracking is beneficial for many applications, such as to enhance safety, security or productivity. Knowing the location of people and mobile equipment may be used to enhance the safety of people on a work site. Knowing the location of patients may enable assistance to rapidly reach them if they fall or press a panic button. Tracking the location of people in a building may allow security staff to be alerted if a person enters an area to which they are not authorised. Determining the location of access points in a building allows a rogue access point to be rapidly found and dealt with. Tracking the movement of staff and materials at a work site allows the operational efficiency to be analysed and possibly improved.
Mobile networks track mobile handsets so that their location for an emergency call can be estimated (e.g. E911 in the USA). This technique has low accuracy, with a typical accuracy many tens to hundreds of meters. The location of handsets with WiFi (e.g. Apple iPhone) can be determined in some areas using the signal strength of multiple access points. However, this only works in areas where there is a sufficient density of access points and a database of their signal strength as a function of location is available.